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Merge pull request #32208 from microsoft/fix31766

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Restore union-like behavior for inference to conditional types
This commit is contained in:
Anders Hejlsberg 2019-07-02 10:01:23 -07:00 committed by GitHub
commit 345777e45e
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5 changed files with 135 additions and 30 deletions
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60
src/compiler/checker.ts
View file

@ -15354,36 +15354,11 @@ namespace ts {
inferFromTypes(getFalseTypeFromConditionalType(<ConditionalType>source), getFalseTypeFromConditionalType(<ConditionalType>target));
}
else if (target.flags & TypeFlags.Conditional && !contravariant) {
inferFromTypes(source, getTrueTypeFromConditionalType(<ConditionalType>target));
inferFromTypes(source, getFalseTypeFromConditionalType(<ConditionalType>target));
const targetTypes = [getTrueTypeFromConditionalType(<ConditionalType>target), getFalseTypeFromConditionalType(<ConditionalType>target)];
inferToMultipleTypes(source, targetTypes, /*isIntersection*/ false);
}
else if (target.flags & TypeFlags.UnionOrIntersection) {
// We infer from types that are not naked type variables first so that inferences we
// make from nested naked type variables and given slightly higher priority by virtue
// of being first in the candidates array.
let typeVariableCount = 0;
for (const t of (<UnionOrIntersectionType>target).types) {
if (getInferenceInfoForType(t)) {
typeVariableCount++;
}
else {
inferFromTypes(source, t);
}
}
// Inferences directly to naked type variables are given lower priority as they are
// less specific. For example, when inferring from Promise<string> to T | Promise<T>,
// we want to infer string for T, not Promise<string> | string. For intersection types
// we only infer to single naked type variables.
if (target.flags & TypeFlags.Union ? typeVariableCount !== 0 : typeVariableCount === 1) {
const savePriority = priority;
priority |= InferencePriority.NakedTypeVariable;
for (const t of (<UnionOrIntersectionType>target).types) {
if (getInferenceInfoForType(t)) {
inferFromTypes(source, t);
}
}
priority = savePriority;
}
inferToMultipleTypes(source, (<UnionOrIntersectionType>target).types, !!(target.flags & TypeFlags.Intersection));
}
else if (source.flags & TypeFlags.Union) {
// Source is a union or intersection type, infer from each constituent type
@ -15481,6 +15456,35 @@ namespace ts {
return undefined;
}
function inferToMultipleTypes(source: Type, targets: Type[], isIntersection: boolean) {
// We infer from types that are not naked type variables first so that inferences we
// make from nested naked type variables and given slightly higher priority by virtue
// of being first in the candidates array.
let typeVariableCount = 0;
for (const t of targets) {
if (getInferenceInfoForType(t)) {
typeVariableCount++;
}
else {
inferFromTypes(source, t);
}
}
// Inferences directly to naked type variables are given lower priority as they are
// less specific. For example, when inferring from Promise<string> to T | Promise<T>,
// we want to infer string for T, not Promise<string> | string. For intersection types
// we only infer to single naked type variables.
if (isIntersection ? typeVariableCount === 1 : typeVariableCount !== 0) {
const savePriority = priority;
priority |= InferencePriority.NakedTypeVariable;
for (const t of targets) {
if (getInferenceInfoForType(t)) {
inferFromTypes(source, t);
}
}
priority = savePriority;
}
}
function inferToMappedType(source: Type, target: MappedType, constraintType: Type): boolean {
if (constraintType.flags & TypeFlags.Union) {
let result = false;

19
tests/baselines/reference/conditionalTypeRelaxingConstraintAssignability.js
View file

@ -21,7 +21,21 @@ export class Elem<
new Elem(undefined as ElChildren.Void);
new Elem('' as ElChildren.Text);
new Elem('' as ElChildren.Void | ElChildren.Text); // error
new Elem('' as ElChildren); // error
new Elem('' as ElChildren); // error
// Repro from #31766
interface I { a: string }
type DeepPartial<T> =
T extends object ? {[K in keyof T]?: DeepPartial<T[K]>} : T;
declare function f<T>(t: T, partial: DeepPartial<T>): T;
function g(p1: I, p2: Partial<I>): I {
return f(p1, p2);
}
//// [conditionalTypeRelaxingConstraintAssignability.js]
"use strict";
@ -37,3 +51,6 @@ new Elem(undefined);
new Elem('');
new Elem(''); // error
new Elem(''); // error
function g(p1, p2) {
return f(p1, p2);
}

44
tests/baselines/reference/conditionalTypeRelaxingConstraintAssignability.symbols
View file

@ -71,3 +71,47 @@ new Elem('' as ElChildren); // error
>Elem : Symbol(Elem, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 8, 83))
>ElChildren : Symbol(ElChildren, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 0, 0), Decl(conditionalTypeRelaxingConstraintAssignability.ts, 2, 20))
// Repro from #31766
interface I { a: string }
>I : Symbol(I, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 22, 27))
>a : Symbol(I.a, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 26, 13))
type DeepPartial<T> =
>DeepPartial : Symbol(DeepPartial, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 26, 25))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 28, 17))
T extends object ? {[K in keyof T]?: DeepPartial<T[K]>} : T;
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 28, 17))
>K : Symbol(K, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 29, 25))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 28, 17))
>DeepPartial : Symbol(DeepPartial, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 26, 25))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 28, 17))
>K : Symbol(K, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 29, 25))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 28, 17))
declare function f<T>(t: T, partial: DeepPartial<T>): T;
>f : Symbol(f, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 29, 64))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 19))
>t : Symbol(t, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 22))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 19))
>partial : Symbol(partial, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 27))
>DeepPartial : Symbol(DeepPartial, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 26, 25))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 19))
>T : Symbol(T, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 19))
function g(p1: I, p2: Partial<I>): I {
>g : Symbol(g, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 31, 56))
>p1 : Symbol(p1, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 33, 11))
>I : Symbol(I, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 22, 27))
>p2 : Symbol(p2, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 33, 17))
>Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --))
>I : Symbol(I, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 22, 27))
>I : Symbol(I, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 22, 27))
return f(p1, p2);
>f : Symbol(f, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 29, 64))
>p1 : Symbol(p1, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 33, 11))
>p2 : Symbol(p2, Decl(conditionalTypeRelaxingConstraintAssignability.ts, 33, 17))
}

27
tests/baselines/reference/conditionalTypeRelaxingConstraintAssignability.types
View file

@ -62,3 +62,30 @@ new Elem('' as ElChildren); // error
>'' as ElChildren : ElChildren
>'' : ""
// Repro from #31766
interface I { a: string }
>a : string
type DeepPartial<T> =
>DeepPartial : DeepPartial<T>
T extends object ? {[K in keyof T]?: DeepPartial<T[K]>} : T;
declare function f<T>(t: T, partial: DeepPartial<T>): T;
>f : <T>(t: T, partial: DeepPartial<T>) => T
>t : T
>partial : DeepPartial<T>
function g(p1: I, p2: Partial<I>): I {
>g : (p1: I, p2: Partial<I>) => I
>p1 : I
>p2 : Partial<I>
return f(p1, p2);
>f(p1, p2) : I
>f : <T>(t: T, partial: DeepPartial<T>) => T
>p1 : I
>p2 : Partial<I>
}

15
tests/cases/compiler/conditionalTypeRelaxingConstraintAssignability.ts
View file

@ -21,4 +21,17 @@ export class Elem<
new Elem(undefined as ElChildren.Void);
new Elem('' as ElChildren.Text);
new Elem('' as ElChildren.Void | ElChildren.Text); // error
new Elem('' as ElChildren); // error
new Elem('' as ElChildren); // error
// Repro from #31766
interface I { a: string }
type DeepPartial<T> =
T extends object ? {[K in keyof T]?: DeepPartial<T[K]>} : T;
declare function f<T>(t: T, partial: DeepPartial<T>): T;
function g(p1: I, p2: Partial<I>): I {
return f(p1, p2);
}